[alsa-devel] [alsa-lib][PATCH v2 0/2] ctl: deprecate APIs of dimension information

[Takashi Sakamoto]

Hi,

This patchset is to update my previous one:
[alsa-devel] [alsa-lib][PATCH 0/2] ctl: deprecate APIs of dimension information
http://mailman.alsa-project.org/pipermail/alsa-devel/2017-November/126972.html

In ALSA control interface of asound.h, 'struct snd_ctl_elem_info' has
'dimen' member to deliver information for multi-dimensional array, however
there's no common way to handle the member. As a result, drivers can
force userspace applications to handle the information by inconsistent
ways. A series of echoaudio drivers is an actual example of the
inconsistent usage.

This issue was addressed in a commit 51db452df07b ('Revert "ALSA: echoaudio:
purge contradictions between dimension matrix members and total number of
members"') to Linux kernel[1]. Fortunately, at present, this feature of
interface is just used by the drivers, and there's a way to obsolete usage
of the feature. We can obsolete it without large impacts to userland.

As a result of discussion at Linux miniconference 2017, usage of 'dimen'
member of 'struct snd_ctl_elem_info' is going to be deprecated for future
removal. This patchset is for proposed tasks at a development period of
Linux kernel v4.15[3]. Some APIs of dimension information are deprecated.

In a short discussion in my previous patchset, it's clear that actual
removal of kernel interface is uncertain depending on several conditions.
Thus the timing to remove the library APIs is not decided yet. This updated
version reflects the issue in API documentation (but simply removes
statement of the schedule...).

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/sound/pci/echoaudio?id=51db452df07bb4c5754b73789253ba21681d9dc2

[2] [alsa-devel] [ANNOUNCE] Audio Mini Summit 2017 at Prague, Oct 27
http://mailman.alsa-project.org/pipermail/alsa-devel/2017-July/123110.html

[3] https://github.com/takaswie/presentations/blob/master/20171027/contents.md

Takashi Sakamoto (2):
  ctl: deprecate APIs of dimensional information
  test: obsolete usage of APIs of dimensional information

 src/control/control.c       |  9 +++++++++
 test/user-ctl-element-set.c | 31 -------------------------------
 2 files changed, 9 insertions(+), 31 deletions(-)

-- 
2.14.1